Not memorising contemporary case studies can pose an obvious deficit in nuance. I would definitely recommend to know the ins and outs of real contemporary case studies.
As for your comment on memorising, I get it! Very few of us are blessed with a good memory haha. But if you stick with one company, it becomes much easier to memorise, especially if you're recalling them weekly/fortnightly.
And sticking with 1/2 companies is completely fine! You have to remember, HSC markers go question by question so they're not going to know you've stuck with one company.